Wednesday, October 25, 2017

Consult Rounds: Podocytic infolding glomerulopathy( PIG)

Podocytic infolding glomerulopathy( PIG)

What is PIG? – This is a pathology based finding seen rarely in the EM section of the report. It is a form of  glomerulopathy, in which microspheres or microtubular structure or both are associated with infolding of cytoplasmic processes of podocytes into the glomerular basement membrane.  This type of glomerulopathy is not included in the World Health Organization’s classification of glomerular diseases but has been noticed in few cases reports and large case series from Japan.


Associations: In the largest series from Japan,  most patients might have a subtype of lupus, nephritis  class V, or membranous glomerulonephritis.  MCTD, Sjogren's syndrome and tumor lysis syndrome was also found. Interestingly, hydronephrosis was associated with most patients seen with this entity. There have been cases associated with Myeloma as well. 


Electron micrograph shows cytoplasmic  processes of podocytes infolded into the GBM. At the end of an infolded cytoplasmic process of podocyte, microspheres or microtubular structures or both were found. b The infolded cytoplasmic process of a podocyte went through the middle layer of the GBM, which was accompanied by thickening of the lamina densa.

The pathogenic mechanism of PIG is unknown. Hydronephrosis was found in three of 25 patients.  However, no study has shown that experimental hydronephrosis can induce podocytic infolding.In the large series from Japan, all had GBM thickening, and IF was negative in many, followed by some that had only C1q,c3 and some with a full house pattern.  Membranous GN is the most common light microscopy finding followed by FSGS and MPGN.  In an earlier report, some might have called this entity  Membranous glomerulopathy with spherules.

Some researchers performed an immunohistochemical study of complement C5b-9 complexes in several human kidney diseases and have shown positive reactions on round extracellular particles and on striated membranous structures in the GBM. Therefore, the mechanism of podocytic infolding might be related to the role of special types of complement activation in situ on the microstructure.  We don’t know if infolding of the podocyte cytoplasm may be a pattern of GBM/podocyte disruption rather than a true disease entity. However, the diffuse extent and severity of PIG raise the suspicion of defects in the repair mechanism.

Worth a read as we learn about this new entity!

Here are some interesting references



Sunday, October 1, 2017

In the NEWS: Point of Care ultrasound of the Lungs and the Nephrologists


Typical B-line (left) and the standard definition by Lichtenstein (right).Point of care US is increasingly being used in many medical specialties. Nephrology is catching along swiftly as well.  A recent review by our team led by Ross et al discuss the role of Lung US in the ESRD population.  After a systematic review,  we concluded that lung US can be used to determine volume status in chronic ESRD patients by using the B-line score model( see figure above from paper) as discussed in the paper.


As nephrologists, we should be using this in practice and help diagnose and prognosticate high risk patients and perhaps prevent re-admissions.

The role of lung ultrasonography in nephrology practice requires further research regarding its clinical applications. We stated in our paper the following amazing ways it can be used in clinical practice..
i.            What is the role of lung ultrasonography in the management of AKI in the intensive care unit? Could it be used as an endpoint for continuous renal replacement therapy?
ii.            Given the association of mortality with the presence of B-lines in the chronic dialysis population, what is the role of lung ultrasonography in the management of the patient on chronic HD? Could B-lines be used to guide need for increased ultrafiltration and would this change long-term outcome?
iii.            Could lung ultrasonography be used to guide diuretic therapy in patients with chronic cardiorenal syndrome?
iv.            As B-lines detect subclinical volume expansion, could lung ultrasonography be useful in differentiating hypervolemic from euvolemic hyponatremia?

Where can one learn to get point of care US training?
The Emory US course is the mecca of US training: check out the details here
NKF Spring Clinical Meetings 2017 had a course run by us as a pre-course specifically on point of care US. Similar course will be prepared for 2018
KidneyCon 2018 will also be having a hands on workshop for Point of care US training

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